Locks are commonly provided as a security measure, such as to secure the entry doors to houses or other buildings. One type of lock comprises a lock cylinder operatively associated with a bolt that is provided in the door. A key can be inserted into the lock cylinder to actuate the bolt, extending it into the door frame to lock the door, or retracting it from the door frame to unlock the door. This type of lock is typically referred to as a deadbolt lock. Other types of locks are also commercially available.
Most locks are operable by a key. Typically the key is fabricated from a thin strip of metal that can be inserted into the lock cylinder. The key aligns pins in the lock cylinder so that the lock cylinder can be turned to actuate the bolt. Other types of keys include “smart cards” commonly used for hotel room doors, and key fobs commonly used for remote operation of car door locks.
Of course nearly everyone has locked their keys inside of their house or car at one time or another. Likewise, from time-to-time homeowners may want to leave a key out for their friend to use when the owner is away (e.g., to enter the home and care for their pets). Accordingly, many people will hide a spare key outside of the house that can be retrieved and used when the homeowner locks their key inside of the house or that their friend can use when the homeowner is away. Unfortunately, the hiding places that most people use are near the door (e.g., under the doormat) and are the first places that would-be thieves tend to look.
Combination locks offer an alternative to key-operated locks. Combination locks eliminate the need for a key and hence spare keys. However, drawbacks include the need to memorize the combination code, and the time it takes to enter the combination code each time the door needs to be opened. Once the combination code is known by someone else, the lock must be changed or a new combination code must be assigned to the lock to prevent later entry by the unauthorized individual having knowledge of the original combination code. In addition, combination locks, as with key-operated locks, can be “picked”.
Pattern-recognition systems have also been developed that can be used to actuate locks in place of a key or a combination code. These systems may employ a laser that scans an object (e.g., a human eye) for unique patterns. Sophisticated software analyzes the unique pattern and actuates the lock when it recognizes the unique pattern. However, the types of unique patterns that these systems can identify are typically restricted (e.g., to only eyes). In addition, these systems are very expensive and therefore use is often limited to areas requiring extreme security measures.